Möbius 3

MIDI Tracks are a recent feature of Mobius 3. They allow you to record and play MIDI loops in much the same way as audio tracks. MIDI tracks also support a number of options that audio tracks do not have, making them useful for pre-recorded drum loops or backing tracks that change their size and tempo to match audio tracks recorded live.

To start using MIDI Tracks you must add one or more of them in the session. See the Sessions document for details on configuring tracks.

Once you have MIDI tracks, you control them by sending them functions or parameter changes using Bindings just like audio tracks. Many of the same functions for recording audio tracks work with MIDI tracks, these include:

• Reset
• Record
• Overdub
• Multiply
• Insert
• Replace
• Mute
• Pause
• Start
• Stop
• Loop Switch
• Undo
• Redo

In addition, MIDI tracks support parameters like Sync Source and Sync Unit to record synchronized tracks, and Quantize Mode to control when functions occur.

To help identify MIDI tracks, the track number in the UI will displayed in a different color than the audio track numbers. It is also recommend that you give them names in the session.

Configuring MIDI Devices

You must start by configuring one or more MIDI devices for Mobius to use. Mobius has two modes of operation: as a Standalone application and as a Plugin. The way you go about getting MIDI into and out of Mobius may be different depending on which operating mode you are using.

Configuring Direct MIDI Devices in Standalone Mode

When you run Mobius standalone, it must connect directly to MIDI devices. From the Configuration menu select MIDI Devices, the MIDI Devices window will appear. This window contains a table of all the devices that were discovered connected to your computer. To receive MIDI from a device, click on the Input Devices tab and locate the MIDI device you want to use. Check the box in the column named App Enable. Assuming you want to send MIDI to a device, click the Output Devices tab and do the same thing in the output devices table.

There is an area at the bottom of this window where status messages are displayed when Mobius tries to connect to a device. Depending on the MIDI device drivers you are using, you may see an error here if another application is already using this device.

Configuring MIDI Devices in Plugin Mode

When you run Mobius as a plugin, there are two ways for it to use MIDI. You can open Direct MIDI Devices as is done in standalone mode, or you can let the host be in control of the devices and arrange to have MIDI messages routed through the host and into Mobius. How this is done is a complex topic and is different for every host. If you have ever used a synthesizer plugin, the process is similar. The Mobius plugin has “ports” to receive and send MIDI messages, and you need to route MIDI messages into and out of those ports.

In some cases you may also want to have the Mobius plugin directly open MIDI devices and not route messages through the host. This is especially the case if you want to generate MIDI clocks which are much more sensitive to timing irregularities than notes. To directly open MIDI devices as a plugin, use the Midi Devices table and check the boxes in the “Plugin Enable” columns. Note that a common problem is if the host is also connecting to MIDI devices, attempting to have Mobius connect to the same devices may result in an error because the MIDI device driver does not support “multi client” mode. You will need to disable those devices in the host application in order to make direct connection in Mobius.

Configuring MIDI Tracks to use Devices

Once you have selected the MIDI devices to connect to, you need to tell each MIDI track which of those devices to use for input and output. This is done in the session editor. Select the track you wish to configure in the track table, click General in the parameter tree and look at the General Parameters form:

In this example, the Midi Input menu is open showing the names of the devices you have configured for input. Selecting Any means the track will receive from all devices that are enabled. If Mobius was running as a plugin, you would also see the name Host in the list. Choose Host if you want to receive MIDI messages through the host application rather than directly from a device.

Next, open the Midi Output menu and select the desired output device. Unlike the input device where Any can be used to receive from all devices, a track can only send to one output device.

Recording MIDI Tracks

You record MIDI tracks just like audio tracks. First select a MIDI track by giving it focus. The focused track is displayed in the UI with a white box around it. If you are using the standard bindings, press the R key on the keyboard or whatever button on your controller you have bound to the Record function. The track will begin recording. Play some notes on your keyboard, do press Record again. The loop will begin playing and you should year the notes you played during recording.

Once you have a MIDI loop recorded, you can modify it using many of the same functions that are available to audio tracks including Overdub, Mute, and Replace. I’m not going to outline how every function behaves, they are mostly the same as they are for audio tracks except for a few differences due to the way MIDI data works.

The most important things to understand about MIDI notes is the envelope and output level. When a MIDI note is sent to a synthesizer, it normally starts applying an envelope which changes the sound you hear over time. The most common of these is the ADSR envelope. THe longer you hold a note, the longer the distance into the envelope you go. This is commonly used to make sounds that have a sharp percussive attack, then gradually decay as the note is held. If you record one long note into Mobius you will hear the full range of the envelope being applied by the synth.

Where MIDI tracks start differing substantially from audio tracks is what happens when you edit them. Anything you do that splits a note or changes the beginning or end will impact how the envelope is being applied by the synth. For example if you start with one long note, then use Replace to insert a gap in the middle, you will end up with two MIDI notes, and both of these will start the envelope generator over from the beginning. Similarly, if you have a long MIDI note and you do something that trims off the first half of it, the portion of the note that remains will not sound the same as it did before, the envelope generator will start over when the start of the trimmed note is reached.

How the output level control behaves is a bit less obvious. MIDI 1.0 doesn’t really have the notion of an output level, at least not the way we think of them in a mixer. There are two ways you can adjust the percieved volume of a note, using a continuous control (CC) message that is implemented as the Volume controller, or by adjusting the velocity of the note. The problem with using the Volume CC (if your synth even implements it) is that it applies to all notes on that channel, not just the notes in the Mobius track you are changing. Mobius attempts to simulate audio track output level by applying a reduction to the velocity of each note that is sent by the track. This can achieve a similar effect, but it will depend entirely how you have programmed the synth to respond to note velocity.